S-91251A544 1/4"-20 x 1 1/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress industrial applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black-oxide finish prolongs service life in harsh environments, minimizing maintenance and replacement costs.
• Precise Class 3A thread fit provides secure, vibration-resistant connections, enhancing assembly integrity and reducing loosening over time.
• High Rockwell C37 hardness offers excellent wear resistance, maintaining thread integrity and drive engagement through repeated use.
• Coarse UNRC threads enable faster installation and reduced cross-threading risks, saving time and labor in production settings.
• Hex socket drive design allows for high-torque application in confined spaces, improving accessibility and installation efficiency.
• Full threading along the 1-1/4" length ensures consistent grip and adjustability, accommodating various material thicknesses with a single fastener type.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in demanding industrial environments, such as machinery assembly, automotive systems, and heavy equipment manufacturing. The coarse 1/4"-20 UNRC threads and Class 3A fit provide superior resistance to vibration-induced loosening, a common failure point in dynamic applications. The black-oxide surface treatment significantly enhances corrosion resistance without compromising the high tensile strength of the underlying alloy steel, making it ideal for outdoor or chemically exposed settings. By combining ASTM A574 compliance with a fully threaded design, this fastener delivers consistent clamping force and ease of installation, reducing assembly time and improving long-term reliability in precision engineering projects.

Specification Summary & Compliance

This socket head cap screw adheres to ASTM A574 specifications, ensuring consistent quality and performance. It features 1/4"-20 coarse UNRC threads with a precision Class 3A thread fit for secure fastening. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, meeting environmental and safety standards for industrial use.